The present invention relates to a compound. More especially, the present invention relates to an adjuvant for use in a vaccine. In a more particular embodiment, the present invention relates to a glycoside adjuvant.
In the majority of vaccines used to date antibodies are raised against proteins that are present on the surfaces of disease-causing (pathogenic) organisms (e.g. viruses, bacteria). Vaccine formulations typically contain inactivated or killed pathogens. In many situations it is desirable to elicit an antibody response against a particular set of proteins, peptides or carbohydrates that are present in the pathogen. This leads to a well-defined response which can be targeted against proteins that are highly conserved between different strains of the pathogen, thereby achieving a broader-based immunity.
Furthermore, the ability to stimulate both class I- and class II-restricted immune responses is deemed to be important because it leads to a more comprehensive level of immunity than is currently achieved with existing vaccines.
Briefly, class II-restricted responses involve the production of antibodies that are specific to the proteins or peptides used in the vaccinexe2x80x94this is often referred to as the humoral immune response.
Class I-restricted immune responses are cell-mediated responses that are responsible for detecting and dealing with viral infections. In contrast to the class II-restricted responses, class I responses involve the activation of CD8+ cytotoxic T lymphocytes (CTLs). These CTLs are activated by oligomeric peptides that are derived from non-self proteins. These peptides are presented at the surface of cells in conjunction with the products of the major histocompatibility complex I (MHC-1). Activated CTLs are able to recognise and destroy virus-infected cells that have non-self oligopeptides on their surfaces.
The use of adjuvants in vaccine formulations leads to enhanced immune responses, particularly against soluble proteins and peptides which are only weakly immunogenic.
Several adjuvants have been described in the literature (e.g. complete or incomplete Freund""s adjuvant) but most are only of experimental interest because of their severe inflammatory side-effects. So far, saponin-based adjuvants are believed by some to be amongst the most promising because of their activity and their relatively low toxicity and inflammatory side-effects.
By way of example, EP-A-0231039 discloses the use of a saponin glycoside as an adjuvant for vaccines. These particular adjuvants, which are in the form of nanoparticles, are characterised by their unique architectures and are often referred to as immunostimulatory complexes (ISCOMS). These are produced by mixing a saponin glycoside and cholesterol in aqueous solutions, often in the presence of a lipid and detergent, followed by one or more purification steps. The saponin is present in at least its critical micellar concentration (CMC). The ability of ISCOMS to elicit high antibody titres against a wide range of antigenic proteins and peptides has been demonstrated as has their ability to induce CTL activity (i.e. the ISCOM nanoparticles can stimulate both class I- and class II-restricted immune responses).
However, there is still a continuing need to develop adjuvants for vaccines, in particular adjuvants that can stimulate class I-restricted and/or class II-restricted immune responses to naturally occurring or synthetic proteins and oligopeptides.
According to a first aspect of the present invention there is provided an alkaloid glycoside for use in medicine.
According to a second aspect of the present invention there is provided an alkaloid glycoside for the stimulation of a class I-restricted immune response and/or a class II-restricted immune response.
According to a third aspect of the present invention there is provided an alkaloid glycoside for use as a vaccine adjuvant.
According to a fourth aspect of the present invention there is provided the use of an alkaloid glycoside in the manufacture of a medicament for use as a vaccine.
According to a fifth aspect of the present invention there is provided the use of an alkaloid glycoside as an adjuvant in the manufacture of a medicament for use as a vaccine.
According to a sixth aspect of the present invention there is provided the use of an alkaloid glycoside in the manufacture of a medicament to stimulate a class I-restricted immune response and/or a class II-restricted immune response.
According to a seventh aspect of the present invention there is provided a process of preparing a composition comprising admixing an agent capable of inducing an immune response with an alkaloid glycoside, wherein the agent is in an amount to cause an induction of an immune response and wherein the alkaloid glycoside is in an amount for use as an adjuvant.
According to an eighth aspect of the present invention there is provided a process of preparing a composition comprising admixing an agent capable of inducing an immune response with an alkaloid glycoside, wherein the agent is in an amount to cause an induction of an immune response and wherein the alkaloid glycoside is in an amount to cause stimulation of a class I-restricted immune response and/or a class II-restricted immune response.
According to a ninth aspect of the present invention there is provided a method of treatment, the method comprising administering to a subject a composition wherein the composition comprises an agent capable of inducing an immune response within the subject and wherein the composition also comprises an alkaloid glycoside, wherein the agent is in an amount to cause an induction of an immune response and wherein the alkaloid glycoside is in an amount for use as an adjuvant.
According to a tenth aspect of the present invention there is provided a method of treatment, the method comprising administering to a subject an alkaloid glycoside, wherein the alkaloid glycoside is in an amount to cause stimulation of a class I-restricted immune response and/or a class II-restricted immune response.
According to an eleventh aspect of the present invention there is provided a method of treatment, the method comprising administering to a subject in need of treatment a composition wherein the composition comprises an agent capable of inducing an immune response within the subject and wherein the composition also comprises an alkaloid glycoside, wherein the agent is in an amount to cause an induction an immune response and wherein the alkaloid glycoside is in an amount to cause stimulation of a class I-restricted immune response and/or a class II-restricted immune response.
According to a twelfth aspect of the present invention there is provided the combination of an alkaloid glycoside and an agent capable of inducing an immune response.
According to a thirteenth aspect of the present invention there is provided the combination of two or more compositions for sequential or consecutive administration to a subject, wherein at least one composition comprises an alkaloid glycoside and at least one other composition comprises an agent capable of inducing an immune response.
Thus, the present invention is based on the surprising finding that it is possible to use an alkaloid glycoside for a medical usuage, in particular for the stimulation of a class I-restricted immune response and/or a class II-restricted immune response. This finding is highly surprising as R. Bomford, M. Stapleton, J. E. Beesley, E. A Jessup, K. R. Price, G. R. Fenwick (in xe2x80x9cAdjuvanticity and ISCOM formation by structurally divests saponinsxe2x80x9d; Vaccine, vol.10, (1992), 572-577.) state that glycoalkaloids (i.e. alkaloid glycosides) lack adjuvant activity.
The term xe2x80x9csubjectxe2x80x9d includes any one or more different types of animal, including humans. Preferably, the term means a human.
The term xe2x80x9cglycosidexe2x80x9d as used herein means a derivative of a sugar (which may be a simple sugar or a complex sugar) in which the hydroxyl group attached to carbon 1 of the sugar is substituted by an alcoholic, or other, aglycone group.
In a preferred embodiment, the term xe2x80x9cglycosidexe2x80x9d as used herein means a chemical entity/substance comprising a steroid, triterpene or other polycyclic aliphatic structure and one or more carbohydrates.
The term xe2x80x9calkaloid glycosidexe2x80x9d as used herein means a glycoside capable of combining with acids to form salts.
In a preferred embodiment, the term xe2x80x9calkaloid glycosidexe2x80x9d as used herein means a glycoside where the aglycone group is a steroid, triterpene or other polycylic aliphatic structure which contains at least one nitrogen heterocycle (i.e. a heterocyclic group comprising at least N).
Preferably, the nitrogen heterocycle is a derivative of pyrrolidine, piperidine, imidazoline, piperazine, morpholine, pyridine, quinoline, isoquinoline, or pyrimidine.
Preferably the alkaloid glycoside is substantially (virtually) water insoluble.
Preferably, the term xe2x80x9csubstantially (virtually) water insolublexe2x80x9d means having a solubility of less than 300 mg per 1000 cc H2O.
Examples of suitable alkaloid glycosides may include tomatine, chaconine commersonine, demissine, solanine and solasonine.
For the present invention the alkaloid glycoside may be a specific alkaloid glycoside or it may be a mixture of alkaloid glycosides.
Preferably, the alkaloid glycoside is at least tomatine (viz. (3xcex2, 5xcex1, 22xcex2, 25S)-Spirosolan-3-yl O-xcex2-D-glucopyranosyl-(1-2)-O-[xcex2-D-xlopyranosyl-(1-3)]-O-xcex2-D-glucopyranosyl-(1-4)-xcex2-D-galactopyranoside).
Preferably, the alkaloid glycoside is tomatine.
In each of the aspects of the present invention the alkaloid glycoside may be used in combination with one or more other adjuvants, such as saponin glycoside.
In each of the aspects of the present invention the alkaloid glycoside may be used in combination with one or more pharmaceutically acceptable carrier(s) and/or diluent(s) and/or excipient(s).
In each of the aspects of the present invention the alkaloid glycoside may be used in combination with one or more other active agent(s).
The composition of the present invention may be used for prophylactic treatment or for curative treatment.
Preferably, the composition of the present invention may be used for prophylactic treatment.
Preferably, the composition is a vaccine composition.
Preferably, the composition of the present invention is translucent.
Preferably the method of treatment is a method of vaccination or immunisation.
In the method of treatment, the alkaloid glycoside may be administered atxe2x80x94or delivered toxe2x80x94a different site on or in a subject than some or all of the agent that is capable of inducing an immune response.
Preferably, the immune response is at least partial vaccination or immunisation.
More preferably, the immune response is substantial vaccination or immunisation.
In a preferred aspect, the agent capable of inducing an immune response is a protein or oligopeptide.
Typically, the protein or oligopeptide is isolatable from a virus, a bacterium, a parasite, or an animal cell.
In a more preferred aspect, the agent capable of inducing an immune response is a naturally occurring protein or oligopeptide or a synthetic protein or oligopeptide.
Here the term xe2x80x9csyntheticxe2x80x9d includes proteins or oligopeptides made by recombinant DNA techniques and/or proteins or oligopeptides made by synthetic chemical techniques.
Preferably, the protein or oligopeptide is equivalent to a T cell epitope.
For some applications, the protein or oligopeptide may be water soluble.
Preferably, the term xe2x80x9cwater solublexe2x80x9d means xe2x80x9d means having a solubility of at least 300 mg per 1000 cc H2O.
For some applications, the protein or oligopeptide may be more water soluble than the alkaloid glycoside.
More preferably the protein or oligopeptide is weakly immunogenic. The term xe2x80x9cweakly immunogenicxe2x80x9d means that when administered in the absence of adjuvants, the agent induces less than a tenfold increase in antibody titres or less than 45% cell lysis in an assay of CTL activity.
For some applications, preferably the protein or oligopeptide is substantially purified prior to admixture with the alkaloid glycoside.
With the present invention, the alkaloid glycoside may be used in combination with one or more agents capable of inducing an immune response.
For some applications, preferably the alkaloid glycoside is used in combination with one specific type of agent capable of inducing an immune response.
Preferably, the alkaloid glycoside of the present invention is used to stimulate both class I-restricted and class II-restricted immune responses.
More preferably, the alkaloid glycoside of the present invention is used to stimulate both class I-restricted and class II-restricted immune responses to naturally occurring or synthetic proteins and oligopeptides.
In the combination aspect of the present invention, the alkaloid glycoside need not necessarily be admixed with the agent capable of inducing an immune response. Preferably, however, the alkaloid glycoside is admixed with the agent capable of inducing an immune response.
In a preferred aspect, the alkaloid glycoside may be admixed with an agent that is capable of suppressing the haemolytic activity of the alkaloid glycoside.
A preferred agent that is capable of suppressing the haemolytic activity of the alkaloid glycoside is a sterol.
Preferred sterols that are capable of suppressing the haemolytic activity of the alkaloid glycoside are sterols of animal or plant origin and may include any one or more of cholesterol, stigmasterol, lumisterol.
A highly preferred agent that is capable of suppressing the haemolytic activity of the alkaloid glycoside is cholesterol.
In a preferred aspect, the alkaloid glycoside may be admixed with a solubiliser for the alkaloid glycosidexe2x80x94particularly if the alkaloid glycoside is substantially insoluble in water.
In a preferred aspect, the solubiliser is a detergent.
Suitable detergents include any one or more of a non-ionic detergent, an ionic detergent, and a zwitterionic detergent.
Preferably, the detergent is at least a non-ionic detergent.
Preferably, the detergent is a non-ionic detergent.
A preferred detergent is xcex2-octylglucopyranoside.
If a detergent is used, then preferably the detergent is removed from the composition that is to be used for the method of treatment. In this regard, the art is replete with techniques to remove detergents. By way of example, the detergent is removed by dialysis, chromatography or gradient centrifugation. Preferably, the detergent is removed by dialysis.
The composition of the present invention may also include other componentsxe2x80x94such as one or more lipids.
In a more preferred aspect, the composition of the present invention thus comprises tomatine, cholesterol, a non-ionic detergent, and saline. Cholesterol is present to suppress the haemolytic activity of tomatine. Since tomatine is virtually insoluble in water, the non-ionic detergent is employed to solubilise it. The mixture is dialysed against saline to remove the detergent. In this way the adjuvant formulation is obtained as a translucent dispersion.
With the present invention, the alkaloid glycoside may be administered subsequent to, and/or consecutive with, and/or prior to administration of the agent capable of inducing an immune response. Preferably, at least some of the alkaloid glycoside is administered consecutively with at least some of the agent capable of inducing an immune response.
For some applications, preferably at least a substantial proportion of the alkaloid glycoside is administered consecutively with at least a substantial proportion of the agent capable of inducing an immune response.
With the present invention the some or all of the alkaloid glycoside may be administered in the same composition as some or all of the agent capable of inducing an immune response.
Alternatively, the alkaloid glycoside may be administered in a different composition as the agent capable of inducing an immune response.
Preferably, the alkaloid glycoside is administered in the same composition as the agent capable of inducing an immune response
The present invention will now be described by way of example only. In the following examples, room temperature was 20xc2x0 C.